Related Field
The present invention relates to a method for forming a three-dimensional article according to the preamble of claim 1.
Description of Related Art
Freeform fabrication or additive manufacturing is a method for forming three-dimensional articles through successive fusion of chosen parts of powder layers applied to a worktable. A method and apparatus according to this technique is disclosed in US 2009/0152771.
Such an apparatus may comprise a start plate on which said three-dimensional article is to be formed, a powder dispenser, arranged to lay down a thin layer of powder on the start plate for the formation of a powder bed, a ray gun for delivering energy to the powder whereby fusion of the powder takes place, elements for control of the ray given off by the ray gun over said powder bed for the formation of a cross section of said three-dimensional article through fusion of parts of said powder bed, and a controlling computer, in which information is stored concerning consecutive cross sections of the three-dimensional article. A three-dimensional article is formed through consecutive fusions of consecutively formed cross sections of powder layers, successively laid down by the powder dispenser.
In US 2009/0152771 it is provided a camera for capturing an Infrared-radiation image, more particularly this camera is used for detecting irregularities in a newly applied powder layer. The irregularities may, according to US 2009/0152771, be caused by irregular applying of the powder on the working table or contamination in the powder dispenser or impurities in the powder as such. There is a need in the art for a method and apparatus in which the cause for irregular powder distribution may be detected for future repair in the additive manufacturing system.